Where's the best place for Upsells to live?
Contributor 
I've found that it's often valuable to keep CS focused on making customers successful and maximizing retention, passing upsell opportunities to sales. That way, it feels cleaner for the customer as well -- this person is here to help be succeed, not sell me stuff.
I've also used SPIFs to incentivize CSMs to uncover opportunities, that they then pass over to sales.
What are others doing here? Do most of you have opportunities passed to Sales, or do you have CS teams handle upsell, and if so does that create any issues?